This invention relates to an interruption circuit for use in combination with a central processing unit in interrupting operation of the central processing unit when the central processing unit receives an interruption signal from one of a multiplicity of interruption generating units or interruption sources and when the central processing unit identifies that one of the interruption generating units.
For use in combination with such an interruption circuit, each interruption generating unit is for generating an interruption signal upon occurrence of an interruption requesting phenomenon which is herein called an interruption request. The interruption circuit comprises a scanning arrangement between the central processing unit and the multiplicity of interruption generating units for scanning the interruption generating units to specify one of the interruption generating units at a time as a particular unit. The scanning arrangement supplies the interruption signal generated by the particular unit to the central processing unit as a particular signal.
In a conventional interruption circuit which will later be described more in detail, the scanning arrangement supplies the central processing unit additionally with an identification signal which identifies the particular unit. Supplied with the particular signal and the identification signal, the central processing unit interrupts its operation related to the particular unit. It takes an appreciably long time for the central processing unit to receive the identification signal and as a consequence to actually interrupt the operation after the interruption signal is generated by the particular unit.